Study inclusion criteria were patients who underwent a single treatment of first-time PRP, with a minimum of 1000 spots in a 360-degree fashion. Exclusion criteria included any history of optic neuropathy, glaucoma, ocular hypertension, and poor scans that could not be re-segmented. Pre-PRP SD-OCTs were completed, using a Heidelberg Spectralis OCT, in all patients and compared to SD-OCTs done at all follow-up visits. To compare the data over time, the SD-OCTs were divided in 6 post-PRP groups (1-60, 61-120, 121-240, 241-360, 361-480, and >480 days). Data was normalized by measuring percent-change from pre-PRP values. A two-sided, pairwise, t-test for the mean was used to determine the significance of RNFL changes from baseline.

Results

22 eyes from 17 patients were enrolled in the study. The 1-60 day post-PRP scans showed statistically significant RNFL thickening in global thickness (10.8±0.9%, p=0.004) as well as the inferonasal (10.1±1.0%, p=0.002), inferotemporal (11.1±1.0%, p=0.001), temporal (13.0±1.5%, p=0.007), and supratemporal (7.1±0.7%, p=0.003) regions. After 60 days, there was a return to baseline RNFL thickness that was maintained throughout the follow-up period (see figure 1).

Conclusions

Following PRP, there is an initial thickening of the peripapillary RNFL followed by a return to pre-PRP thickness. In patients with PDR and glaucoma, RNFL thickness measured by SD-OCT can be used reliably to monitor for progression of disease beginning 60 days after PRP, especially in those whose laser pattern may affect visual field results.